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Sauropod neck laryngeal nerve

From: Ben Creisler

In advance papers for Acta Palaeontologica Polonica:

Mathew J. Wedel (2011)
A monument of inefficiency: the presumed course of the recurrent laryngeal
nerve in sauropod dinosaurs.
Acta Palaeontologica Polonica in press
available online 20 May 2011 doi:10.4202/app.2011.0019

The recurrent laryngeal nerve is an oft?cited example of "unintelligent
design" in biology, especially in the giraffe. The nerve appears early in
embryonic development, before the pharyngial and aortic arches are
separated by the development of the neck. The recurrent course of the nerve
from the brain, around the great vessels, to the larynx, is shared by all
extant tetrapods. Therefore we may infer that the recurrent laryngeal nerve
was present in extinct tetrapods, had the same developmental origin, and
followed the same course. The longest?necked animals of all time were the
extinct sauropod dinosaurs, some of which had necks 14 meters long. In
these animals, the neurons that comprised the recurrent laryngeal nerve
were at least 28 meters long. Still longer neurons may have spanned the
distance from the end of the tail to the brainstem, as in all extant
vertebrates. In the longest sauropods these neurons may have been 40?50
meters long, probably the longest cells in the history of life. 

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